Liquid-Fertilizer Ready Formulations of Bifenthrin

ABSTRACT

Insecticidal compositions suitable for use in preparation of insecticidal liquid fertilizers are disclosed. The compositions include bifenthrin, a polymeric dispersant, a suspension agent, a freeze-thaw stabilizer, and optionally a preservative.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit under 35 U.S.C. § 119(e) of U.S.Provisional Application Ser. No. 61/912,259, filed Dec. 5, 2013, thedisclosure of which is incorporated herein by reference in its entirety.

TECHNICAL FIELD

The presently disclosed subject matter relates to the field ofagrochemical compositions and formulations. In particular, the presentdisclosure includes an insecticidal composition that includes bifenthrinin combination with a polymeric dispersant. Compositions include thosesuitable for use in the preparation of insecticidal liquid fertilizers.

BACKGROUND

To enable the efficient elimination or control of unwanted insects incombination with providing nutrients for plants to combat adverseenvironmental conditions (such as heat, drought, physical contact withanimals, etc.) it is desirable to formulate an effective chemicalinsecticide for use in preparation of insecticidal liquid fertilizers.Formulations of insecticides combined with fertilizers are desirable inagricultural and related endeavors due to the multiple benefits conveyedby just one application in a single piece of equipment. One applicationof such a combination or formulation provides nutrients for the plantgrowth, while eliminating or controlling unwanted insects that can alsoaffect the health and vitality of the desirable plants.

Mixtures containing insecticide compositions and liquid fertilizers havebeen practiced in the art, but problems with the physical stability ofsuch mixtures have caused application and efficacy issues. When atraditional insecticidal composition is combined with a liquidfertilizer, particularly a high-phosphate starter fertilizer, thecombined components (surfactants, viscosity modifiers, wetting agents)of both can cause accelerated physical degradation (phase separation) ofthe mixture. This physical degradation can occur in the mix tanks priorto application on the plants. Often this problem goes unnoticed andresults in inconsistent application of both the fertilizer andinsecticide, yielding inadequate efficacy of both.

SUMMARY

In one aspect, the present invention is directed to an insecticidalcomposition comprising a) bifenthrin; b) a polymeric dispersant; andoptionally, c) a suspension agent selected from the group consisting ofattapulgite clay, fumed silica and combinations thereof. Another aspectis directed to an insecticidal composition that includes a) bifenthrin;b) a polymeric dispersant; c) a suspension agent selected fromattapulgite clay, fumed silica and combinations thereof; d) afreeze-thaw stabilizer; and optionally, e) a preservative.

In one embodiment, the polymeric dispersant is selected from the groupconsisting of polyacrylic acids, polymethacrylic acids, copolymersthereof and salts thereof. In one specific embodiment the polymericdispersant is selected from the group consisting of polyacrylic acidsand salts thereof. In one preferred embodiment the polymeric dispersantis a salt of polyacrylic acid, having an average molecular weightbetween about 1000 and about 100,000 Daltons. In one preferredembodiment the salt of the polyacrylic acid comprises a sodium salt. Inanother preferred embodiment the salt of the polyacrylic acid is asodium salt. In one embodiment the suspension agent is present, and isfumed silica. Preferably, the insecticidal composition comprises a)about 15% to about 30% of bifenthrin; b) about 0.2% to about 20% of apolymeric dispersant; c) 0% to about 20% of a suspension agent selectedfrom the group consisting of attapulgite clay, fumed silica andcombinations thereof; d) from about 1% to about 10% of a freeze-thawstabilizer, and e) from 0% to about 1% of a preservative, where all %are % by weight based on the total weight of all components in thecomposition. The composition can further comprise one or more additivesselected from the group consisting of surfactants, wetting agents,anti-foam agents, preservatives and biocides. In one embodiment, thefreeze-thaw stabilizer comprises ammonium sulfate. In anotherembodiment, the freeze-thaw stabilizer is ammonium sulfate.

Another aspect of the invention is directed to an insecticidal liquidfertilizer composition wherein the insecticidal composition furthercomprises a liquid fertilizer. Preferably, the liquid fertilizer isaqueous-based. In one embodiment, the liquid fertilizer is present in aconcentration of about 95.0% by weight to about 99.99% by weight basedon the total weight of all components in the composition. Preferably,the other components of the insecticidal liquid fertilizer compositioninclude bifenthrin in about 0.75% to about 1.25%, and the suspensionagent in about 0.05% to about 1.0%, based on the total weight of allcomponents in the composition. In one embodiment, the polymericdispersant is selected from the group consisting of polyacrylic acids,polymethacrylic acids, copolymers thereof and salts thereof. In onespecific embodiment the polymeric dispersant is selected from the groupconsisting of polyacrylic acids and salts thereof. In one preferredembodiment the polymeric dispersant is a salt of polyacrylic acid,preferably a sodium salt, having an average molecular weight betweenabout 1000 and about 100,000 Daltons. The liquid fertilizer compositioncan further comprise one or more additives selected from the groupconsisting of freeze-thaw stabilizers, surfactants, wetting agents,anti-foam agents, preservatives and biocides. In one embodiment, thefreeze-thaw stabilizer is present and comprises ammonium sulfate. Inanother embodiment, the freeze-thaw stabilizer is ammonium sulfate.

DETAILED DESCRIPTION

In accordance with the present disclosure, it has now been found that anew insecticidal composition significantly improves physical stabilitywhen used to prepare an insecticidal liquid fertilizer. Accordingly, inone aspect, the present disclosure provides an insecticidal compositionthat includes bifenthrin, a polymeric dispersant, and optionally, asuspension agent selected from clays and colloidal silicas. Anotheraspect is directed to an insecticidal composition that includesbifenthrin; a polymeric dispersant; a suspension agent selected fromattapulgite clay, fumed silica and combinations thereof; a freeze-thawstabilizer, and optionally, a preservative.

The modifier “about” is used herein to indicate that certain preferredoperating ranges, such as ranges for molar ratios for reactants,material amounts, and temperature, a not fixedly determined. The meaningwill often be apparent to one of ordinary skill. For example, arecitation of a temperature range of about 120° C. to about 135° C. inreference to, for example, an organic chemical reaction would beinterpreted to include other like temperatures that can be expected tofavor a useful reaction rate for the reaction, such as 105° C. or 150°C. Where guidance from the experience of those of ordinary skill islacking, guidance from the context is lacking, and where a more specificrule is not recited below, the “about” range shall be not more than 10%of the absolute value of an end point or 10% of the range recited,whichever is less.

The term “ambient temperature” as utilized herein shall mean anysuitable temperature found in a laboratory or other working environment,and is generally not below about 15° C. nor above about 30° C.

“Dispersants”, or “dispersing agents”, are substances added to asuspension of solid particles, typically a colloidal suspension, toimprove the separation of the particles and to decrease or preventsettling or clumping. As used herein, the term “polymeric dispersants”includes those dispersant substances having a bona fide polymericstructure. In one embodiment, the polymeric dispersants includesynthetic homopolymers or copolymers. In one aspect, the polymericdispersants in the compositions provided herein are selected frompolyacrylic acids, polymethacrylic acids, other acidic polymers,particularly polymers bearing carboxylic acid (CO₂H) groups, copolymersthereof, salts thereof, and combinations thereof. The SOKALAN® productsof BASF Corporation are representative polymeric dispersants. Apreferred product is SOKALAN® PA 30 CL polyacrylic acid dispersant,which is an aqueous dispersion of a low molecular weight polyacrylicacid, fully neutralized as the sodium salt, having an average molecularweight of about 8000 Daltons. Preferably, the average molecular weightof the polymeric dispersant is between about 1000 and about 100,000Daltons. In one embodiment the average molecular weight is from about1000 to about 10,000 Daltons. In one embodiment the average molecularweight of the polymeric dispersant is about 8000 Daltons. Salts of thepolymeric dispersant can include, without limitation, ammonium,alkylammonium, dialkylammonium, trialkylammonium, sodium, potassium, andthe like. Salts can also comprise mixtures of various cations.

In one embodiment, the clay is selected from montmorillonite,attapulgite, and combinations thereof. In one embodiment, the clay hasan average particle size of about 0.1 micron. The ATTAFLOW® products ofBASF Corporation are representative. A preferred product is ATTAFLOW®FL, which is an aqueous suspension of attapulgite.

Colloidal silicas include, but are not limited to, fumed silicas. In oneembodiment, the fumed silica is a hydrophilic fumed silica. TheAERODISP® products of Evonik Industries are representative. A preferredproduct is AERODISP® W 7512 S, which is an aqueous dispersion ofhydrophilic fumed silica. Fumed silicas form colloidal suspensionshaving desirable thickening, suspending and stabilizing properties inagricultural formulations.

In one aspect, the present disclosure provides an insecticidalcomposition that includes a) bifenthrin; b) a polymeric dispersant; andoptionally, c) a suspension agent. As used herein, the term “suspensionagent” also includes thickeners and/or thickening agents. Another aspectis directed to an insecticidal composition that includes a) bifenthrin;b) a polymeric dispersant; c) a suspension agent selected from the groupconsisting of attapulgite clay, fumed silica and combinations thereof;d) a freeze-thaw stabilizer, and optionally, e) a preservative. In oneembodiment the suspension agent is selected from clays, silicas, orcombinations thereof. In one embodiment, the clay includes attapulgite.In one aspect, the silica includes a fumed silica. In one embodiment,the polymeric dispersant is selected from the group consisting ofpolyacrylic acids, polymethacrylic acids, copolymers thereof, saltsthereof, and combinations thereof. In another embodiment, the polymericdispersant is selected from polyacrylic acids or salts thereof. In oneembodiment, the polymeric dispersant includes a salt of polyacrylicacid, having an average molecular weight between about 1000 and about100,000 Daltons. In one preferred embodiment the salt of the polyacrylicacid includes the sodium salt. The acidic functionality of the polymericdispersant can be totally neutralized or partially neutralized as asalt.

In one preferred embodiment, the suspension agent includes fumed silica.

In one aspect, the insecticidal composition includes a) about 5% toabout 40%, preferably about 10% to about 35%, more preferably about 15%to about 30%, still more preferably about 15% to about 25% ofbifenthrin; b) about 0.1 to about 30%, preferably about 0.2% to about20%, more preferably about 1% to about 15% of a polymeric dispersant;and c) 0% to about 30%, preferably about 0.1% to about 30%, morepreferably about 1% to about 20%, still more preferably about 3% toabout 10% of a suspension agent selected from the group consisting ofattapulgite clay, fumed silica and combinations thereof; where all % are% by weight based on the total weight of all components in thecomposition. In one embodiment, the polymeric dispersant is present inan amount of about 11% by weight based on the total weight of allcomponents in the composition. In one embodiment, the suspension agentis attapulgite, present in an amount of about 10% by weight based on thetotal weight of all components in the composition. In anotherembodiment, the suspension agent is fumed silica, present in an amountof about 3.5% by weight based on the total weight of all components inthe composition.

Optionally, the composition further includes one or more additivesselected from freeze-thaw stabilizers, surfactants, wetting agents,anti-foam agents, preservatives and biocides. In one embodiment, thesurfactant is selected from anionic surfactants, alkyld-glucopyranosides and mixtures of two or more thereof. In oneembodiment, the alkyl d-glucopyranoside surfactant includes a mixture ofC₉-C₁₁ alkyl d-glucopyranosides. The AGNIQUE® products of BASFCorporation are representative. A preferred product is AGNIQUE® PG9116,which is a mixture of C₉-C₁₁ alkyl d-glucopyranosides, having a degreeof polymerization of about 1.6 and a hydrophilic-lipophilic balance(HLB) of about 13.1. In one embodiment, the anionic surfactant includesan alkylbenzene sulfonic acid salt, preferably a sodium salt.Representative anionic surfactants include the STEPWET® products ofStepan Corporation. A preferred product is STEPWET® DF-90, which is thesodium salt of dodecylbenzene sulfonic acid.

In one embodiment, the freeze-thaw stabilizer includes a polyalkyleneglycol, preferably propylene glycol, present in an amount from about 1%to about 10% by weight, preferably about 5% to about 10% by weight ofthe total of all components in the composition, preferably about 9% byweight. In one embodiment, the freeze-thaw stabilizer includes ammoniumsulfate (AMS), and is present in an amount from about 1% to about 10% byweight, preferably about 5% to about 10% by weight. In one embodiment,AMS is present in about 9% by weight. AMS provides additional benefitsto the formulation by also serving as a fertilizer and as a densitymodifier for the aqueous formulation. “Freeze-thaw stabilizers” are alsoknown as “antifreeze agents”.

In an embodiment, the anti-foam agent includes analkylcyclotetrasiloxane, preferably an octamethylcyclotetrasiloxanesilicone emulsion, for example, DOW CORNING® AF Emulsion or DOWCORNING®ANTIFOAM C Emulsion (Dow Corning Corporation). When present, theanti-foam agent is present in an amount of from about 0.001% to about 1%by weight of all the components in the total formulation.

The preservative can be an isothiazolinone or a mixture ofisothiazolinones, for example, KATHON® CG/ICP preservative (a mixture of5-chloro-2-methyl-4-isothiazolin-3-one and2-methyl-4-isothiazolin-3-one), or LEGEND® MK preservative (Rohm andHaas Corporation), or PROXEL™ BR preservative (Avecia Corporation). Whenpresent, the preservative is present in an amount of from about 0.001%to about 1% by weight of the total of all components in the formulation.Preservatives include, but are not limited to, biocidal compounds,antimicrobial compounds, and the like.

In one embodiment, the present disclosure provides an insecticidalcomposition that includes a) bifenthrin; b) a polymeric dispersantselected from polyacrylic acids, polymethacrylic acids, copolymersthereof, salts thereof, and combinations thereof; optionally c) asuspension agent selected from attapulgite clay, fumed silica andcombinations thereof; d) an anionic surfactant; and e) a freeze-thawstabilizing agent. Another embodiment is directed to an insecticidalcomposition that includes a) bifenthrin; b) a polymeric dispersantselected from polyacrylic acids, polymethacrylic acids, copolymersthereof, salts thereof, and combinations thereof; c) a suspension agentselected from attapulgite clay, fumed silica and combinations thereof;d) a freeze-thaw stabilizing agent; and optionally, e) a preservative.In one embodiment, the polymeric dispersant includes a polyacrylic acidor salt thereof. In one embodiment, the anionic surfactant includes analkylbenzene sulfonic acid salt. In one embodiment, the freeze-thawstabilizing agent includes ammonium sulfate. In one embodiment, thesuspension agent c) is absent; in another embodiment the suspensionagent is present.

In one aspect, the present disclosure provides an insecticidalcomposition that includes a) bifenthrin; b) a polymeric dispersantselected from polyacrylic acids, polymethacrylic acids, copolymersthereof, salts thereof, and combinations thereof; c) a suspension agentselected from attapulgite clay, fumed silica, and combinations thereof;d) an anionic surfactant; e) a freeze-thaw stabilizing agent; and f) apreservative. In one embodiment, the polymeric dispersant includes apolyacrylic acid or salt thereof. In one embodiment, the anionicsurfactant includes an alkylbenzene sulfonic acid salt, preferablysodium dodecylbenzene sulfonate. In one embodiment, the freeze-thawstabilizing agent includes ammonium sulfate. In one embodiment, thepreservative includes an isothiazolinone or mixture of isothiazolinones.In one embodiment, the suspension agent includes attapulgite clay; inanother embodiment the suspension agent includes fumed silica.

In one aspect, the present disclosure provides an insecticidalcomposition that includes from about 15% to about 30% of bifenthrin,preferably from about 15% to about 25%; from about 0.2% to about 20% ofat least one polymeric dispersant; and from about 1% to about 20% of asuspension agent selected from attapulgite clay, fumed silica andcombinations thereof, wherein all % are % by weight based on the totalweight of all components in the composition.

Another embodiment is directed to an insecticidal fertilizer compositionthat includes from about 0.75% to about 1.25% of bifenthrin, from about0.1% to about 0.75% of at least one polymeric dispersant, optionally,from about 0.05% to about 1.0% of a suspension agent selected fromattapulgite clay, fumed silica and combinations thereof, and from about95% to about 99.99% of a liquid fertilizer, wherein all % are % byweight based on the total weight of all components in the composition.

The term “liquid fertilizer” refers to a fertilizer in a fluid or liquidform containing various ratios of nitrogen, phosphorous and potassium(for example, but not limited to, 10% nitrogen, 34% phosphorous and 0%potassium) and micronutrients, commonly known as starter fertilizersthat are high in phosphorus and promote rapid and vigorous root growth.Liquid fertilizers are commonly aqueous-based. As used herein, the term“aqueous-based” indicates that the predominant solvent or vehicle iswater.

The present disclosure also encompasses a method of controlling unwantedinsects and providing nutrients to plants, the method includes applyingto an area infested with such insects and containing such plants aneffective amount of a liquid fertilizer in combination with one of thecompositions of this invention.

The present disclosure further encompasses a process for preparing acomposition according to the present disclosure by dispersing bifenthrinin a mixture of water and at least one polymeric dispersant, andoptionally a freeze-thaw stabilizing agent, an anti-foam agent and/or apreservative; wet milling the mixture to an average particle size ofabout 0.1 to about 10 microns, preferably about 1 to about 5 microns,and adding a suspension agent selected from attapulgite clay, fumedsilica, or combinations thereof. The process can further include thestep of adding the resultant mixture to a liquid fertilizer.

The compositions of the present invention are further illustrated by theexamples below. These examples serve only to illustrate the inventionand should not be interpreted as limiting the scope of the invention inany way, since further modifications encompassed by the disclosedinvention will be apparent to those skilled in the art. All suchmodifications are deemed to be within the scope of the invention asdefined in the present specification and claims.

EXAMPLES Example 1. Preparation of Compositions that Include Bifenthrin

Composition 1-1: An amount of 206.8 grams of water was combined with38.0 grams of ammonium sulfate, 2.0 grams of an anionic surfactant(STEPWET® DF 90, Stepan Company), 44.0 grams of an acrylic homopolymer(SOKALAN® PA 30 CL, BASF), 68.6 grams of bifenthrin (100 weight % activeingredient), 40.0 grams of a suspension aid (Attaflow® FL, BASF) and 0.6grams of an isothiazolinone compound mixture (KATHON® CG/ICP, Rohm andHaas Co.) and the mixture was stirred until homogenous. This mixture wasmilled to a particle size of less than 7 microns.

Composition 1-2: An amount of 232.8 grams of water was combined with38.0 grams of ammonium sulfate, 2.0 grams of an anionic surfactant(STEPWET® DF 90), 44.0 grams of an acrylic homopolymer (SOKALAN® PA 30CL), 68.6 grams of bifenthrin (100 weight % active ingredient), 14.0grams of fumed silica (AERODISP® W 7512 S, EVONIK Industries) and 0.6grams of an isothiazolinone compound mixture (KATHON® CG/ICP) and themixture was stirred until homogenous. This mixture was milled to aparticle size of less than 7 microns.

Composition 1-3: An amount of 243.4 grains of water was combined with38.0 grams of ammonium sulfate, 2.0 grams of C₉-C₁₁ alkyld-glucopyranoside surfactant (AGNIQUE® PG9116, BASF Corporation), 44.0grams of an acrylic homopolymer (SOKALAN® PA 30 CL), 68.6 grams ofbifenthrin (100 weight % active ingredient) and 36.0 grams of propyleneglycol and the mixture was stirred until homogenous. This mixture wasmilled to a particle size of less than 7 microns.

Composition 1-4: An amount of 249.4 grams of water was combined with36.0 grams of ammonium sulfate, 2.0 grams of an anionic surfactant(STEPWET® DF 90), 44.0 grams of an acrylic homopolymer (SOKALAN® PA 30CL), 68.6 grams of bifenthrin (100 weight % active ingredient, powderform) and 36.0 grams of ammonium sulfate and the mixture was stirreduntil homogenous. This mixture was milled to a particle size of lessthan 7 microns.

Example 2. Comparative Stability Study

This example sets forth stability studies that were performed oncompositions prepared in accordance with the present invention.

The physical stability of Compositions of Example 1 were tested bymixing the composition with a 11% nitrogen-37% phosphorus-O % potassiumaqueous-based liquid fertilizer at a 5% active ingredient ratio. Amixture of 2.5 mL of a Composition of Example 1 and 47.5 mL of 11-37-0aqueous liquid fertilizer was placed into a glass container, thecontainer was sealed and inverted 30 times to mix well. The mixture waspoured into a 50 mL glass column to observe the mixture's physicalstability. At ten minute intervals a five mL sample of the mixture wastaken and analyzed by HPLC for bifenthrin concentration. The stabilityof each Composition was compared with that of a known formulation ofbifenthrin, an Emulsifiable Concentrate (TALSTAR® 2EC, FMC Corp.) alsomixed in the same aqueous liquid fertilizer. Table 1 summarizes thisdata.

TABLE 1 Physical stability; ppm of bifenthrin in sample over time 0 1020 30 40 50 Composition Minutes Minutes Minutes Minutes Minutes Minutes1-1 2526 3173 2492 3001 4095 3007 1-2 3552 3664 4277 4580 4418 4841TALSTAR ® 9427 7557 7052 5630 4270 2984 2EC

The test data above indicate that the compositions of Example 1 arehomogenous throughout the test, indicating good physical stability,whereas the comparison formulation is not homogenous and has poorphysical stability when mixed with high phosphorus aqueous-based liquidfertilizer.

While this invention has been described with an emphasis upon preferredembodiments, it will be obvious to those of ordinary skill in the artthat variations in the preferred compositions and methods can be usedand that it is intended that the invention can be practiced otherwisethan as specifically described herein. Accordingly, this inventionincludes all modifications encompassed within the spirit and scope ofthe invention as defined by the claims that follow.

What is claimed is:
 1. An insecticidal composition comprising: a)bifenthrin; b) a polymeric dispersant selected from the group consistingof polyacrylic acids, polymethacrylic acids, copolymers thereof, saltsthereof, and combinations thereof; c) a suspension agent selected fromthe group consisting of attapulgite clay, fumed silica, and combinationsthereof, d) a freeze-thaw stabilizer, and e) optionally, a preservative.2. The composition of claim 1, wherein said polymeric dispersant isselected from the group consisting of polyacrylic acids, salts thereof,and combinations thereof.
 3. The composition of claim 2, wherein saidsalt comprises a sodium salt.
 4. The composition of claim 1, whereinsaid suspension agent is fumed silica.
 5. A composition comprising: a)from about 15% to about 30% of bifenthrin; b) from about 0.2% to about20% of a polymeric dispersant selected from the group consisting ofpolyacrylic acids, polymethacrylic acids, copolymers thereof, saltsthereof, and combinations thereof; c) from 0% to about 20% of asuspension agent selected from the group consisting of attapulgite clay,fumed silica, and combinations thereof; d) from about 1% to about 10% ofa freeze-thaw stabilizer, and e) from 0% to about 1% of a preservative,wherein all % are % by weight based on the total weight of allcomponents in the composition.
 6. The composition of claim 5, whereinsaid polymeric dispersant is selected from the group consisting ofpolyacrylic acids, salts thereof, and combinations thereof.
 7. Thecomposition of claim 6, wherein said salt comprises a sodium salt. 8.The composition of claim 5, wherein said suspension agent is fumedsilica.
 9. The composition of claim 1 further comprising a liquidfertilizer.
 10. The composition of claim 9, wherein said liquidfertilizer is aqueous-based.
 11. The composition of claim 10, whereinsaid liquid fertilizer is present in a concentration of about 95.0% byweight to about 99.99% by weight based on the total weight of allcomponents in the composition.
 12. The composition of claim 11, whereinbifenthrin is present in about 0.75% to about 1.25%, the polymericdispersant is present in about 0.1% to about 0.75%, and the suspensionagent is present in about 0.05% to about 1.0% by weight based on thetotal weight of all components in the composition.
 13. The compositionof claim 1, further comprising at least one additive selected from thegroup consisting of surfactants, wetting agents, anti-foam agents,preservatives and biocides.
 14. The composition of claim 5, furthercomprising at least one additive selected from the group consisting ofsurfactants, wetting agents, anti-foam agents, preservatives andbiocides.
 15. The composition of claim 12, further comprising at leastone additive selected from the group consisting of freeze-thawstabilizers, surfactants, wetting agents, anti-foam agents,preservatives and biocides.
 16. The composition of claim 1, wherein saidfreeze-thaw stabilizer comprises ammonium sulfate.
 17. The compositionof claim 5, wherein said freeze-thaw stabilizer comprises ammoniumsulfate.
 18. The composition of claim 12, wherein said freeze-thawstabilizer comprises ammonium sulfate.
 19. The composition of claim 1,wherein said polymeric dispersant comprises a salt of polyacrylic acid,having an average molecular weight between about 1000 and about 100,000Daltons.
 20. The composition of claim 5, wherein said polymericdispersant comprises a salt of polyacrylic acid, having an averagemolecular weight between about 1000 and about 100,000 Daltons.
 21. Thecomposition of claim 12, wherein said polymeric dispersant comprises asalt of polyacrylic acid, having an average molecular weight betweenabout 1000 and about 100,000 Daltons.